We have developed a high-throughput methodology for flow cytometry, HyperCyt(r), that enables automated, quantitative, high-content analysis of 40 or more samples per minute. A long-term goal is to adapt this methodology to high content screening of diverse molecular interactions in cells and cell-free multiplex beadbased assays. A more immediate goal is to screen small molecule compound libraries for structures that block binding of defined fluorescent ligands to receptors expressed on cells. We have established and characterized a homogeneous no-wash HyperCyt(r) assay for sensitive detection of compounds that block ligand binding to the human formylpeptide receptor (FPR) and the FPR family member, FPR-like 1 (FPRL1). Since ligand binding is measured directly, the assays detect active compounds independently of potential complexities in cell physiological response patterns. We propose a minor, easily implemented technical modification, color-coding of FPRL1-expressing cells, to allow integration of FPR and FPRL1 assays into a duplex assay capable of simultaneously measuring compound interactions with both receptors in a single sample. Our FPR screening experience supports a high probability that screening of the NIH Small Molecule Repository will identify novel FPR and FPRL1 ligands amenable to optimization as high affinity biological probes. We expect that such compounds will prove to be important tools with which to advance the understanding and therapy of inflammation-associated diseases. [unreadable] [unreadable]